Method of and apparatus for grinding gears



NOV, 10, 1931. MCMULLEN ET AL 1,83%952 METHOD OF AND APPARATUS FOR GRINDING GEARS Filed Dec. 15; 1925 EEMcMzllefi 742726615: Gleason INVEN'IY'ORS fill. SZeWarZ Patented Nov. 10, 1931 UNITED STATES PATENT OFFICE FREDERICK E.v MCMULLEN, JAMES E. GIIEASON, AND ARTHUR L. STEWART, OI ROCH- ESTER, NEW YORK, ASSIGNORS TO GLEASON WORKS, OF ROCHESTER, NEW YORK,

A CORPORATION OF NEW YORK METHOD OF AND APPARATUS FOR GRINDING GEARS Application filed December 15, 1925. Serial No. 75,553.

This invention relates to a method and apparatus for finishing curved tooth gears, that is, gears whose teeth are curved longitudinally across the face of the blank.

The primary object of this invention is to provide a method and apparatus for finishing the surfaces of gear teeth by grinding, after they have-been cut and hardened, whereby they will have accurately finished and smooth running tooth surfaces.

A further object of the invention is to provide mechanism which will grind the tooth surfaces to the desired finish in a rapid and efficient manner.

Other objects will be apparent hereinafter from the specification and the appended claims.

In the drawings we have illustrated one preferred embodiment of our invention. It will be understood, however, that it is not intended to limit the invention to the particular embodiment shown, but that the invention is capable of various modifications within its scope and the limits of the appended claims.

In the drawings:

Fig. 1 is a side elevational view, showing grinding apparatus constructed according to one embodiment of our invention in grinding engagement with a gear;

Fig. 2 is a plan view of the mechanism shown in Fig. 1 as mounted upon a machine having means for imparting to the tool and gear their required relative movement;

Fig. 3 is a diagrammatic view showing .a grinding wheel, such as might be employed in practising this invention, operating upon a tooth side of a non-generated curved tooth gear; I

Fig. 4 is a diagrammatic view similar to Fig. 3 showing a circular profiled grinding wheel, such as might be employed in practising this invention, operating upon a nongenerated gear having teeth surfaces which are spherical surfaces of revolution; and

Fig. 5 is a diagrammatic view showing the tool of Figf3 in operation upon a tooth side of agenerated gear.

It is customary to grind the .tooth surfaces of a gearv after the same have been cut and heat treated in order to remove from the finished surfaces any imperfections due to the hardening or heat treating process. This invention is intended principally for finishing the tooth surfaces of curved tooth gears especially curved tooth or spiral bevel and hypoid gears, though the invention is equally applicable to spur gears or any other type of cars having longitudinally curved teeth.

11 general, the invention includes the use of a grinding element, preferably a rotary grinding wheel, which is moved, preferably reci rocated, in a curved path across the face of t e gear whose teeth are being finished. In order to make possible a ready understanding of the invention reference may be had to the accompanying drawings in which are illustrated one form of apparatus suitable for practising the invention.

As stated, the invention includes the pro- Vision of a grinding element which is movable in a curved path across the face of the gear. In the drawings the grinding element is shown in the form of a rotary disc grinding wheel 10 which is mounted upon a suitable spindle 11 and which is simultaneously rotated on its axis and moved in a curved path across the face of the gear G. Any suitable means may be employed for imparting to the grinding wheel 10 its combined rotary and curvilinear movement. As shown, the grinding wheel spindle is driven from a shaft 12 through a set of bevel gears 13 and is simultaneously translated about the axis of said shaft 12 by rotation of a crank disc 14 which is connected by means of an adjustable connecting rod 15 with the housing 16 within which the wheel spindle 11 is journaled. This shaft 12 is suitably housed in a member 17 mounted on a plate 19.

In a machine constructed according to this invention, the shaft 12 and the crank disc 14 may be actuated by means of a motor 18 which is mounted upon the plate 19 and which is a connected through a pair of bevel gears 20 with the shaft 12 from which the rotary motion of the grinding wheel spindle and the grinding wheel is derived. This shaft 12 may also be connected through a pair of bevel gears 21 with a rotary shaft 22 which is suitably journaled on the plate 19 and to which is keyed a worm 23 which meshes with and drives a worm wheel 24 which is secured to a shaft-25 which is suitably journaled in the plate 19. The shaft 25 carries at its outer end the crank disc 14. By means of the mechanism described, the grinding wheel will be simultaneously rotated on its axis and reciprocated in a curved path across the face of the gear.

The gear G itself may be suitably mounted upon a spindle 26 journaled'in the head 27 which is pivot-ally adjustable about an axis passing through the apex of the gear to permit positioning of the gear in the proper operating plane. Means will also be provided for withdrawing the tool and gear relatively to each other when one grinding cycle has been completed to permit indexing of the gear so as to present a new portion thereof to be ground when the wheel and gear are reengaged. This means may be of any suitable type, such as ,is ordinarily employed in machines for producing gears of the type described. The indexing means may include an index plate such as indicated at 28 in Fig. 2 or may be of any other suitable character.

A machine constructed according to this invention may be adapted for quantity production to manufacture one special type of gear only or it may be more or less universal in character. In the apparatus shown, the plate 19 is so mounted as to permit positioning of the grinding wheel for finishing gears of different spiral angles and different face widths. For this purpose the plate is mounted for lateral adjustment upon a slide 30, whereby the inding wheel may be moved to and from the blank to take up for wear. This slide 30 is provided with an upright portion 31 which is vertically adjustable upon the upright portion 32 of a frame 33, to permit positioning of the grinding wheel so as to grind gears of different spiral angles or longitudinal tooth curvature. The plate 19 may be secured in any ad usted position on the slide 30 by means of the bolts 34, while the slide 30, which may be adjustedon the upright portion 32 of the frame 33 by the screw 35, may be secured in any ad usted position by the clamps or lugs 36 and the clamping screws 37. The frame 33 1s Itself provided with a laterally extending portion 38 which is slidably ad ustable on the base 40 of the machine. This last adjustment permits of moving the grinding wheel to and from the blank apex to permit of grinding gears of diflerent face widths. The frame 33 may be secured in any 8d]l15t8d position by means of the bolts 41.

The present invention is especially suited for the grinding of curved tooth non-generated gears, or ars produced by the movement of a suita 1e tool across the face of the gear blank while the same is held stationary on its axis. In these gears the tooth profiles are complementary to the profiles ofthe cuttlng tool employed to produce the same. It would be rather impractical to grind such gears with a rotary annular grinding wheel, but the present invention provides a method and an apparatus whereby such gears may be readily finished. In Fig. 3 is illustrated the type of grinding wheel or element which would be employed in this invention to grind the tooth surfaces of a non-generated gear which was cut by a straight sided tool moving in a curved path. The active surfaces of the wheel are straight and it will be noted that there is a full line contact between the active grinding surface 42 and the side surface of the tooth T which is being ground. This line contact will move along the length of the tooth as the grinding wheel moves in its curvilinear path. If it is desired to grind the tooth surfaces of a gear having spherical tooth profiles,'a grinding wheel or element having a complementary circular profile 44 such as shown in Fig. 4 may be employed. The contact between the grinding wheel and the non-generated gear tooth surface will again be a line contact but the arc of a circle instead of a straight line. If it is desired to grind a non-generated gear having any other profile than that illustrated a tool having a suitable profile will be employed. In grinding these gears, the grinding wheel or element will move along the length of the tooth while the blank is held stationary.

While especially adapted for the grinding of non-generated tooth profiles, it will be understood that the invention is applicable also to the grinding of generated gears as indicated diagrammatically in Fig. 5. In the grinding of such gears the motions already described will be imparted to the grinding element, in the case of the disc wheel shown, a simultaneous rotary motion on its axis and a movement in a curved path. In addition there will be impart-ed between grinding wheel or element and the blank a simultaneous rolling motion of the same character as employed in the cutting of the gear. In grinding a generated gear, the contact between the gfinding wheel or element and the tooth proc Fig. 5, at any instant. The grinding wheel or element in grinding either generated or non-generated gears ma be so constructed and operated as to grin two adjacent tooth surfaces simultaneously or may be employed in such manner as to finish only one tooth surface at a time.

Any suitable means may be employed for truing or dressing the active surface or surfaces of the grinding wheel.

While we have described our invention in connection with specific structures, it'is to be understood that the invention is capable of various further modifications and will be a point contact, as illustrated in' of various uses without departing from the intent of the invention orthe sco e of the following claims and that this app ication is intended to cover any adaptatwn's or embodiments, following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the gear art and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

Having thus described our invention, what I we claim is:

1. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in rotating a grinding wheel, having an active surface of curved profile on its axis while reciprocating said wheel in a longitudinally curved path across the face of the gear to be ground.

2. The method of grinding the side tooth surfaces of a longitudinally curved tooth gear which consists in rotating a grinding wheel, having an active surface of curve profile on its axis while simultaneously oscillating said wheel about another axis to move the wheel across the face of the gear.

3. The method of grinding the'side tooth surfaces of a longitudinally curved tooth gear which consists in rotating a grinding Wheel, having an active surface of circular arc rofile on its axis while simultaneously osci lating said wheel about another axis to move the Wheel across the face of the gear.

. 4. In a machine for grinding longitudinall curved tooth gears, a gear su port, an osci latory wheel carrier, a wheel spindle journaled therein, a disc grinding wheel, hav- 1ng an active surface of circular arc profile, secured to said wheel spindle, means for rotating the grinding wheel spindle, and means for simultaneously oscillating said grinding wheel carrierto move the wheel across the face of the gear to be ground.

' FREDERICK E. MCMULLEN. JAMES 'E. GLEASON. ARTHUR L. STEWART. 

